The present invention relates to a network control system realizing unified network management for heterogeneous wireless communication systems. The present invention also relates to a network control apparatus and a mobile terminal used in such a network control system.
It is expected that future mobile communications systems will be provided under a heterogeneous access environment that accommodates various types of wireless systems using different types of wireless schemes including next-generation wireless schemes, in addition to WCDMA (Wideband Code Division Multiple Access), which is the wireless scheme of third-generation mobile communications systems, and wireless LANs.
JPA 2000-32032 and its counterpart European Patent Application No. 98301053.9 disclose a network technique for managing multiple types of wireless systems. In these publications, networks corresponding to the respective wireless systems are constructed, and intersystem handover is implemented by carrying out roaming between networks.
However, this technique has several drawbacks when various types of wireless systems are accommodated in a common network.
In general, a wireless system and an internetwork interface are in one-to-one correspondence. For example, the switching technology for personal digital cellular (PDC), which is called the second-generation mobile communications system, is constructed making use of synchronous transfer mode (STM) aiming mainly at voice conversation services. Accordingly, an STM interface dedicated to PDC is provided to a PDC network. Similarly, the switching technology of the third-generation mobile communications system using WCDMA is constructed making use of asynchronous transfer mode (ATM) that is capable of high-rate data exchange and data transfer using various types of communication formats, such as speech and audio/visual data. Accordingly, an ATM interface dedicated to WCDMA is provided to a WCDMA network.
A PDC network and a WCDMA network are managed, operated, and maintained independently of each other. For this reason, Quality of Service (QoS) cannot be handed over during handover between heterogeneous wireless communication systems. In addition, when a PDC wireless system is added to a WCDMA network, an STM interface dedicated to the PDC system has to be newly added to the WCDMA network, which results in complicated network management and increased cost.